What happens when you stop weight loss injections?

In most cases, some weight comes back. The trials that have looked at this show that people who stop weight loss medicines tend to regain a large share of the weight they lost, usually over the following year. Individual results vary, but the direction is consistent across the studies.

Stopping is a decision to make with your prescriber, not a switch to flip. They can help you plan what to do about eating, activity and follow-up before you stop, and what to watch for afterwards.

The STEP-1 trial tested semaglutide 2.4 mg, the dose used in Wegovy for weight management, alongside lifestyle support. After 68 weeks, participants stopped the medicine. The extension study followed a representative subset of those participants for a further year. The paper is by Wilding and colleagues, published in Diabetes, Obesity and Metabolism in 2022 (doi:10.1111/dom.14725).

By week 120, participants who had taken semaglutide had regained 11.6 percentage points of the weight they had lost. Those who had taken placebo regained 1.9 points. The authors summarise this as participants regaining about two-thirds of their prior weight loss one year after withdrawal. Most cardiometabolic measures also moved back towards their starting levels.

Keep the limits in mind. The extension included a subset of 327 participants, the analyses were described by the authors as exploratory, and the study was funded by the manufacturer. The authors conclude that ongoing treatment appears to be needed to maintain improvements in weight and health.

SURMOUNT-4 looked at tirzepatide, the active ingredient in Mounjaro. All participants first took tirzepatide for 36 weeks in an open-label phase, and lost a mean of 20.9% of their body weight. They were then randomised to continue tirzepatide or to switch to placebo for a further 52 weeks.

From week 36 to week 88, the group that continued tirzepatide lost a further 5.5% on average. The placebo group gained 14.0%. At week 88, 89.5% of the continuing group had kept at least 80% of their lead-in weight loss, compared with 16.6% of the placebo group.

These figures are taken from published summaries of the trial, which was sponsored by the manufacturer. Your own experience may differ, and your prescriber can explain what the figures mean for you.

NICE's guidance on weight loss medicines includes a review point based on early weight loss. For tirzepatide (TA1026) and semaglutide 2.4 mg (TA875), the guidance says treatment should be reconsidered, and possibly stopped, if a person has not lost at least 5% of their starting weight after 6 months on the highest tolerated dose.

For TA1026, the guidance says the person and clinician then decide together whether to continue. Your prescriber will apply the guidance to your situation, and it is worth asking them how and when they will review your progress.

Tirzepatide has a long half-life. The Mounjaro SmPC gives an elimination half-life of about five days, so the medicine can take several weeks to clear after your last dose. The SmPC advises stopping at least one month before a planned pregnancy.

The SmPC also says that tirzepatide may reduce how well oral contraceptives work, particularly after starting or increasing a dose. If you could become pregnant, talk to your prescriber or pharmacist about which contraception to use, both while you take the medicine and after you stop.

• What are my reasons for stopping, and what would a good outcome look like for me?
• When should I come off the medicine, and what happens to my dose beforehand?
• Will I have a follow-up, and what should I monitor myself?
• What support will I have for eating and activity after I stop?
• What is the plan if my weight starts to rise, and what other options are there?
• Do I have surgery or a procedure planned, and what should I tell the team?

Do not stop or change your medicine before a procedure without advice from the team carrying it out. Anaesthetic teams assess each person's risk, and no set pause has been shown to reduce the risk of aspiration.

Medicines are only one part of the plan. Weight regain is common in the trials, and it does not mean you did something wrong. Plan for it, and keep in touch with your prescriber or dietitian if your weight starts to rise.

In the weeks after you stop, it can help to keep a simple record of your weight, what you eat, how active you are and how you feel. Bring that record to your reviews. It gives your GP or prescriber a clearer picture than a single weigh-in, and it helps you spot a change early.

The habits that help most are the same as the general NHS advice on eating and activity. The NHS recommends strengthening activities that work all the major muscle groups on at least two days a week for adults aged 19 to 64. Our guide to eating well on weight loss injections covers the eating side in more detail, and our guide to dietitian-led support explains how to get that help.